Menstrual Cycle Changes in Vagally-Mediated Heart Rate Variability are Associated with Progesterone: Evidence from...

Area of Science:

• Reproductive Endocrinology
• Cardiovascular Physiology
• Autonomic Nervous System Function

Background:

• Cardiac vagal activity, indicated by heart rate variability (HRV), decreases during the luteal phase of the menstrual cycle.
• The specific roles of estradiol (E2) and progesterone (P4) in mediating these cyclical HRV changes remain unclear.

Purpose of the Study:

• To investigate the unique and interactive effects of E2 and P4 on HRV across the menstrual cycle.
• To identify which hormone(s) are primarily responsible for menstrual cycle-related HRV fluctuations.

Main Methods:

• Two studies involving naturally-cycling participants utilizing repeated measures of E2, P4, and HRV.
• Study one: Weekly assessments over four weeks (n=40).
• Study two: Assessments during three specific cycle phases using ovulation testing (n=50).
• Multilevel modeling was employed to analyze hormone-HRV relationships.

Main Results:

• Progesterone (P4) was significantly correlated with HRV; higher-than-usual P4 predicted lower-than-usual HRV within individuals.
• HRV was significantly lower in the mid-luteal phase (elevated P4) compared to other cycle phases.
• Estradiol (E2) showed no significant main or interactive effects on HRV.

Conclusions:

• Progesterone is the primary hormonal driver of menstrual cycle-related HRV fluctuations.
• Estradiol does not appear to significantly influence HRV across the menstrual cycle.
• Future research should explore individual differences and functional consequences of these cyclical HRV changes in women's health.